I downloaded the multibit and followed the instructions but if I doubleclick the multibit-exe.jar then the package-manager will open the archive but the multibit application don't start. I use ubuntu as OS and I need help.

IMPORTANT - Mac users - Make sure you do not lose your wallets when upgrading !

Mac users - DO THIS BEFORE UPGRADING1) Right click on /Applications/MultiBit.app and select 'Show Package Contents'.2) Navigate to the directory 'Contents/Resources/Java' in the application bundle.3) Copy the multibit.wallet and multibit.info files to a safe place.4) If you have any other wallet and info files in this directory, copy them to a safe place.

Enhancements+ German added (Vielen Dank freemoney458).+ Added 'Your Wallets' screen and a wallet picker in the toolbar.+ Added swatch generator on Receive bitcoin and Send bitcoin screens.+ Decreased minimum fee amount to 0.0001 to match bitcoin v0.4 .+ Visual indication of which panel you are on added.+ 'Available to spend' now hidden when amount is equal to estimated balance.+ Added number of blocks as a tool tip to the "Online/ Connecting..." status label.+ MultiBit now supplied as an exe file for Windows.+ User data is now stored in user specific roaming/ application data folders.

Unfortunately there isn't a practical way of importing an arbitrary private key into a multibit wallet at the moment.

The problem is not the insertion of the private key (which Mike Hearn wrote code for months ago) but getting hold of all the relevant transactions for that key. You need these to work out the current balance. Because the multibit/ bitcoinj blockchain does not contain the transactions to get a key's transactions you currently have to re-download the whole blockchain. This of course is too expensive to be practical.

To implement the import of an arbitrary private key for multibit/other bitcoinj clients the best way would be a new server call :'Get me all the transactions relevant for this bitcoin address since the genesis block' and then you could insert the key and the returned transactions into the wallet in one go.

The problem is not the insertion of the private key (which Mike Hearn wrote code for months ago) but getting hold of all the relevant transactions for that key. You need these to work out the current balance. Because the multibit/ bitcoinj blockchain does not contain the transactions to get a key's transactions you currently have to re-download the whole blockchain. This of course is too expensive to be practical.

To implement the import of an arbitrary private key for multibit/other bitcoinj clients the best way would be a new server call :'Get me all the transactions relevant for this bitcoin address since the genesis block'

By server call, you mean a network message to be sent to full clients?You would introduce a privacy issue with such implementation. It would be quite clear to everyone you're very likely the owner of those addresses.I'd argue that a better solution, if one is wanting to upgrade the protocol, is to create a message of the sort "give me the lists of outputs on block X". This would allow you to then query for the blocks that concern you. The privacy risk still exists, but it gets smaller as blocks get larger. Such message would also help bitcoin lightweight clients to remain p2p even when block sizes reach hundreds of megabytes: you wouldn't need to download every new block, as lightweight clients do today, only those in which you have money.

Yes - you are right - a call to a full node asking for that information would be a give-away that you control that address.

(general point: you might think a transaction gives the same information but those are forwarded around the network and hence could be anyones).

I like your idea of being able to get the transaction outputs for a block as an indicator of "if you control one of those transaction outputs, you have bitcoin in this block". I think I will mention that on the bitcoinj mailing list - crediting you of course.

A few questions about your unconfirmed transaction:1) Did it send ok ? (Did you get a 'Bitcoin sent ok' on your send confirm screen after you sent it?).2) Has the recipient received it ok?3) Is your payment on the blockchain ? (You can look at blockexplorer.com and search for the receive address)4) Is it still waiting to be incorporated into a block (unlikely after 24 hours but possible). Have a look at :http://bitcoincharts.com/bitcoin/ and search for the receive address.

Let me know. If it is still waiting to be put in a block then that would be normal. If not then please PM the two logs you have in your <installation directory>/log and I will have a look.(The log files don't have your private keys in them)

A few questions about your unconfirmed transaction:1) Did it send ok ? (Did you get a 'Bitcoin sent ok' on your send confirm screen after you sent it?).2) Has the recipient received it ok?3) Is your payment on the blockchain ? (You can look at blockexplorer.com and search for the receive address)4) Is it still waiting to be incorporated into a block (unlikely after 24 hours but possible). Have a look at : http://bitcoincharts.com/bitcoin/ and search for the receive address.

Let me know. If it is still waiting to be put in a block then that would be normal. If not then please PM the two logs you have in your <installation directory>/log and I will have a look.(The log files don't have your private keys in them)

It looks like the message with the confirmation block for the transaction was either never received or never got into your wallet to confirm the tx.

If you look in the multibit help it explains the 'Available to spend'. Bitcoinj is slightly different to the Satoshi client in that you cannot spend change until it is confirmed. It is the quarter of BTC that is the problem - you have the bitcoin available as a transaction output but multibit is erroneously not allowing you to spend it.

I forgot I moved the logs into your user application directory (so you always have write rights).The directory is different on different platforms and versions of Windows. I will post the directory for each when I get to my big computer (this is from my iPhone).

I will add more logging of the incoming data to MultiBit from the network and see if I can reproduce it and fix it.

EDIT:

Where MultiBit stores logs and the default multibit.wallet

1) See if there is a multibit.properties in MultiBit's current working directory. If there is, use this directory as the application data directory. This is for backwards compatibility and for running everything from a USB drive

Yes I need to put focus traversal on the buttons and text input boxes so that you can tab/ enter between boxes.

Now that the preparation for the EuroBit conference is over I will be working through bug fixes and improvements until Christmas so please post anything you spot here (or raise them directly on github.com/jim618/multibit). I will work through them in order of severity (most likely RylandAlmanza's issue 3 first)

Here is the presentation, backup screencast and script that I made for my MultiBit talk at the European Bitcoin Conference.(The screencast was just in case the network failed or I dropped my laptop etc).

I have been thinking about the mixing of transactions from different private keys and how to avoid it.If you have some transactions that you want to keep completely separate from others, you can do this already in MultiBit as follows:

1) Create a wallet called, say, "My Secret Stash" and create a number of new keys/ receiving addresses in it.Any sends from this wallet will only ever use the bitcoin available from the keys/ addresses in *this* wallet. You can have one wallet for more public addresses (e.g. donation addresses) and another for more private transactions.

2) To send bitcoin to this wallet you need to be careful you do not tie your Secret Stash addresses to your more public addresses.One way to do this would be to use an anonymizer such as bitcoinfog (though they do take a 1% commission). If you do not want to lose 1% then you could just make sure that you send bitcoins to your Secret Stash addresses using addresses less traceable to you - say the bitcoin faucet.

3) To keep them separate you must NEVER send directly from your public addresses to your secret addresses as you have then linked them publically on the blockchain.

For the import of private keys - it is something I would like to do but it runs into a technical limitation that I outlined on an earlier post - https://bitcointalk.org/index.php?topic=43616.msg621480#msg621480 Until I have a way to efficiently look up the transactions for a private key (or have the transaction outputs for all blocks) I cannot really implement it in a way that is usable for the general user.